The invention refers to a drilling device including at least one guide element, a carriage movable alone the guide element and a drilling member removably mountable on the carriage. The carriage has a receiving region for the drilling member.
In order to drill holes having a large diameter in a hard substrate, drilling devices are used that consist of a guide element, a carriage that can be moved along the guide element and a drilling member that is removably attached to the carriage.
A drilling device disclosed in U.S. Pat. No. 4,614,456 is attached to a carriage by means of a connection region of the drilling device that can be connected in a form-fitting manner to a receiving region of the carriage. A first receiving section of the receiving region forms a tightening lever which, in an end part facing the connection region, has a tightening surface that interacts with the clamping surface of the connection region. A part of the connection region is secured in a form-fitting manner to a second receiving section of the receiving area.
The tightening surface of the tightening lever can be moved against the force of a spring in a direction facing away from the connection region. The tightening element is formed by the piston rod of a compressed air-driven cylinder that can be moved perpendicularly to the direction of movement of the tightening lever. The tightening lever and the piston rod forming the tightening element both have corresponding slanted surfaces with each other. When the piston rod is moved, the tightening lever is moved in a direction facing away from the connection region and the connection region is tightened against the receiving region. In order to prevent the drilling member from becoming detached from the carriage, it must be ensured that the cylinder is supplied with sufficient compressed air for the entire duration of the work on a substrate. A major drawback of this prior art drilling device is its dependence on a source of compressed air. Moreover, this additionally present compressed-air feed line has a negative effect on the overall handling of the drilling device.
The primary object of the invention is to provide a tightening device including a carriage that can be manufactured economically, to which the drilling member can be affixed quickly, simply and in a self-tightening way, while it can be released from the carriage without additional tools.
On the basis of the embodiment of the drilling device according to the invention, after the drilling member has been secured onto the receiving region of the carriage, a tightening lever pivots into a tightened position in which the drilling member is securely connected to the carriage.
In order to be able to achieve the high tightening force needed in the area of the tightening surface so as to affix the drilling device to the carriage, the tightening lever is preferably configured as a two-arm lever in which the tightening surface is situated on a shorter, first lever arm while the end region of a longer, second lever arm has a tightening surface that faces away from the drilling member and interacts with a tightening element in the tightened position of the tightening lever.
For economic reasons, the tightening element advantageously consists of a part in the form of a pin that extends parallel to a rotational axis of the tightening lever. The pin has, for example, a circular cross section.
A proper and uniform guidance of the tightening element along the tightening surface of the tightening lever is achieved in that the tightening element advantageously runs in two guide grooves on the carriage arranged opposite one another and that extend approximately parallel to the lengthwise extension of the guide column.
The spring-loaded tightening element interacts with two springs that engage the tightening element at a certain distance from each other. To allow a movement of the tightening lever from a tightened position into a release position, the tightening element can advantageously be moved along the guide grooves against the force of the two springs, opposite to the drilling direction, into a release position that releases the tightening lever.
To be able to move the tightening elementxe2x80x94which has been pulled into a tightened positionxe2x80x94into an open position in which the tightening lever can be swiveled into the release position, it is necessary to exert a force on the tightening element that exceeds the spring force of the two springs. Preferably, this force is exerted by means of a release lever arranged on the carriage so as to swivel.
Advantageously, between the release lever and the tightening element, there is a push rod that has a passage opening at a first free end region through which the tightening element passes. A second end region of the push rod is provided with an elongated hole that extends parallel to the elongated push rod. A guide bolt positioned on the release lever projects into this elongated hole and the guide bolt can transmit to the tightening element a release force exerted on the release lever.
The tightening element of the drilling device according to the invention can be held in a pre-stressed, open position by the tightening lever, which is in a release position. For this purpose, on the face that forms the free end of the second lever arm, the tightening lever advantageously has a retention surface that can be connected to the tightening element. When the drilling member is being secured to the receiving area of the carriage, the tightening lever swivels into a tightened position. In this process, the tightening element slides along the retention surface until it is pulled along the tightening surface by the springs into a tightened position in which the tightening lever is locked.